To manufacture semiconductor products requires many processes such as a process for manufacturing a pure silicon wafer, a process for forming a plurality of semiconductor chips on the pure silicon wafer, an electrical die sorting (EDS) process for determining whether the semiconductor chips are good or bad, a package process for packaging good semiconductor chips, and a test process for finally testing the packaged semiconductor chips.
Chips determined to be bad via the EDS process are repaired or removed before an assembly process. This reduces the cost of the assembly process and enhances the yield of the overall chip-fabricating process.
Apparatuses for the EDS process are disclosed in U.S. Pat. Nos. 6,118,290, 6,353,221, and 6,170,116. In a typical apparatus for the EDS, a wafer is placed on a chuck. A tester, to which a probe card is connected, is disposed over the chuck. The probe card has probe needles that are electrically interconnected to chips formed on the wafer to check electric properties.
Generally, a chip pad is made of aluminum. When the EDS process is repeatedly carried out, aluminum-containing foreign materials become attached to the end of the probe needle or damage the end of the probe needle due to repeated contact therewith. Thus, a signal is non-uniformly transmitted, which administers a distorted test.
A mounting plate is disposed at one side of a chuck. To remove the foreign materials attached to the probe needle, a polishing pad such as sandpaper is mounted on the mounting plate. After the polishing pad is used for predetermined time, the end of the probe needle is brought into contact with the polishing pad to clean the probe needle.
A polishing pad gradually is consumed through normal use and eventually must be replaced. However, since a mounting plate is fixed to a chuck in a typical apparatus, it is difficult to monitor whether the polishing pad needs to be replaced and a significant amount of time is required for replacing the polishing pad. That is, to replace the polishing pad or check whether the polishing pad should be replaced, the chuck must be moved to a position in which an operator can visually check the polishing pad with his/her eyes. Afterwards, if replacement of the polishing pad is needed, the chuck is unset to expose the polishing pad such that it can be replaced. After replacing the polishing pad, the chuck must be reset before subsequent processes can be performed.